Machine for manufacturing propeller blades by copying



June 18, 1940. P. J. PFRATIE 2,204,696

IACBINE FOR IAIUFACTURING PROPELLER BLADES BY COPYING Filed Dec. :51; 1951 s Sheets-Sheet 1 w Y F I VENT R:

. PAULIN JEAN PIERRE RATIE.

BY M,

J1me 1940. P. J. P. RATIE 2,204,695

IACHINB FOR IANUFACTURING PROPELLER BLADES BY COPYING Filed Dec. 31, 1937 a Sheets-Sheet z Fiabh INVENTOR; PAULIN JEAN PIERRE RATIE A+ T'OR N EYS 'June 18, 1940. P. J- P. RATIE 0 IACHIHB FOR IAHUFACTURING PRDPELLER BLADES BY COPYING Filed Dec. 31, 1937 8 Sheets-Sheet 3 PAUL lN JEAN PIER v 5v W June 18, 1940.

P. J. P.RAT|E MACHINE FOR MANUFACTURING PROPELLER BLADES BY COPYING Filed Dec. 31, 1937 8 Sheets-Sheet 4 I v INVENTO Q; P/ JN JEAN PIERRERATIE s ATTORNEYS Jpme 18, 1940. P. J. P. RATIE IIAGHINE FOR IMIUFACTURING PROPEL LER BLADES BY COPYING Filed Dec. 31, 1937 8 Sheets-Sheet 5 HflVE'NTOR PAL/LIN JEAN PIERRE RA-rni BY 8 g: ATTORNEXS June 18, 1940. P. .1. P. RATIE 2,204,696

BY COPYING MACHINE FOR HANUFACTURING PROPELLER BLADES Filed Dec. 31, 1937 8 sheetsvsheet 6 4 ENTOR PAULJN JEAN PIERRE; RATn BY 9Q ATTORNEYS June 18, 1940. P. J. RATIE 2,204,696

- IACHINE FOR IANUFACTURING PROPELLER BLADES BY COPYING I Filed Dec; :51, 19:7 8 Shets-Sheet 7 I VENTOR:

PAULIN JEAN PIERRE RATIE',

- Y I ATTORNEYTS,

June 18, 1940. J. P. RATIE 5 MACHINE-FOR MANUFACTURING PROPELLER BLADES BY COPYING Filed Dec. 31, 1937 Y a Sheeis-Sheet 8 BY %v% Ai'TORNEYS .atente d June 18,1940

UNITED STATES PATENT OFFICE MACHINE FOR MANUFACTURJNG PR0 HELLER. BLADES BY COPYING Paulin Jean Pierre Rati, Montrouge, Seine,

France Application December 31, 1937, Serial No. 182,819

In France January 4, 1937 4 Claims.

ilade and at least one blank; the pattern blade 1 ,nd the blank both have. a rotary movement ,bout their axis and, of course, the rotations are ynchronous.

(b) Two systems, each comprising a feeler in ontact with thepattern. blade and a tool in conact with the blank, are'movable transversely to he blades; the feelers and the tools of the two ystems act respectively on the opposite faces of he blades against which they are pressed by prings, counterw'eights, or equivalent means.

(0) Finally, means are provided whereby the radle supporting the blades, and the systems which are movable transversely, are given a rel- .tive movement of translation parallel with the ads of rotation of the blades, which movement 5 imparted either to the cradle, or to a carriage v upporting the movable systems.

The invention relates more particularly to the ype of machines of the above referred to kind :1 which the feelers and the tools, in their trans erse movement with respect to the blades, rotate .boutan axis which in principle is parallel with he axis of rotation of the blades, excluding the ype in which the feelers and the tools have a ectilinear movement perpendicular to the axis If rotation of the blades.

The-invention has for its object to overcome he' drawbacks of this type of machine. Said lrawbacks are set forth in the ensuing descripion together with the characteristics of the in- 'ention, reference being had to the acompanyng diagrammatical drawings which. are only :iven by way of example.

In said drawings:

Fig. 1 shows a known machine having a single movable system with rectilinear movement. .Fig. 2 is a diagram relating to said machine.

Fig. 3 shows a known machine having a double novable system with curvilinear movement.

Fig. 1 is a diagram relating to one of the movable systems of this machine.

Fig. 5 is a diagram relating to the other movtble system of said machine.

i Fig. 6 shows .a first embodiment of a machine according to the invention,

.Figs.. 7 to 18 are diagrams liagrammatical illustrations.

Fig. 19. shows a second embodiment of an im- II'OVEd machine according to the invention.

and explanatory The known machine shown in Fig. 1 comprises a fixed bed I which, by means of headstocks such as 2 and 3, supports on the one hand a pattern blade 4, and on the other hand a blank 5 to be worked; A motor, not shown, drives in synchronism the blade 4 and the blank 5 with a rotary movement in the direction indicated by the arrow I.

Inside the bed I, a. carriage 6 is adapted to move longitudinally, that is to say parallel with the axes of rotation of the blade 4 and of the blank 5. The movement of the carriage 6 is produced automatically in the. well known manner by a worm which has not been shown, since this feed mechanism is very well known, it being in all respects similar to the one which feeds the carriage of a lathe. Furthermore, inside the carriage 6 is a second carriage I which is movable perpendicular to the axes of rotation of the blade 4 and of the blank 5. The carriage I receives, by means-of a support 8, a feeler 9 which is held constantly in contact with the pattern blade 4 by the pull of a cable II] on which is suspended a weight M.

Said weight could be replaced by a spring or a pneumatic pressure. l2, the carriage I carries atool l3 such as a milling cutter, which a motor not shown rotates in the direction of the arrow F. It is obvious that if the milling-cutter I3 is of the same diameter as the feeler 9, said milling cutter will give on the blank -5 a contour which is exactly identical with that of the blade 4.

In Fig. 2, has been shown the diagram of the distances and the diagram of the speeds of the movement of translation of the carriage I perpendicular to the axis of rotation of the pattern blade 4. Said blade has been shown diagrammatically by a straight line for the sake of simplicity. The blade rotates about the shaft l4, and its movement has been studied throughout the period in which the feeler 9 moves away from the axis of rotation l4 under the thrust produced by the rotation of the blade 4. The latter successively takes up the positions 4-4 --4 -4 and 4 The feeler 9 successively takes up the positions |5l5**-l5' --|5 and Hi The successive positions 01 the spindle -l5 have been plotted along the axis OX, and the angles successively formed by the blade 4 have been plotted along the axis OY. The curve E of the distances is thus obtained. The curve V of the speeds is very easily deduced therefrom, since said curve is the substitution, at each point, of the'tangent at the different points of the curve E For example, to

By means of asupport the point A where the slope of the curve B is maximum, there corresponds the point B of the maximum of the curve V In order to plot the ordinate BC of said point B, it sufiices to draw the tangent AD to the curve E at the point A, to draw a straight line AF parallel with CY and equal to the unit chosen, then draw FD parallel with X.; It then sufiices to make-BC equal to It is observed that the variation of the speeds is considerable, that is to say that the maximum ordinate BC is great. This observation explains the fact that on the machines of the type blade 4 and consequently that the tool l3 alsov came out of contact with the blank 5. This phenomenon had led constructors to increase, without appreciable result, the mass of the counterweight H, or again to increase the strength of the retracting spring of the carriage I, or again the pneumatic pressure replacing the spring. These means only form palliatives and had the drawback of excessively increasing the pressure on the blade 4 and on the blank 5.

In the machine shown in Fig. 3, there are two movable systems. Only one of same has been shown in Fig- 1, but it can be readily conceived that two of them could have been shown. However, the explanation would not be improved thereby since what has been stated in connection with one of the movable systems could have been stated identically for the other. The same does not apply to Fig. 3, because the movable systems of this figure are rotatively movable about the shaft l6, instead of being movable in a straight line in the transverse direction relatively .to the pattern blade 4 and the blank 5.

As in the previous example, the pattern 4 and the blank are rotated by a motor, not shown, in the direction of the arrow 1. The feeler 9 and the tool l3 are mounted at the end of each of the arms of the lever I! which rotates on the shaft It, a counterweight l8 compelling the feeler 8 to remain in contact with the blade 4. Of course, the lever I1 is given, as before, an automatic movement of translation along the shaft l8 and the tool 13 is rotated inthe direction of the arrow 1 The second movable system is shown in dotted lines. It is composed of identically the same members as the previous one, and its members have been designated by the same reference numerals but with an index.

In Fig. '4 a diagram has been drawn in the same manner as in the case of Fig. 2, it will therefore not be necessary to repeat how said diagram has been constructed. It will be noted that the spindle l5 successively takes up the positions I5-I5"----I5 --l5 =--I5 and l5 and that the curve of the distances, which is visible at E corresponds to the projections of the curvilinear displacement of the spindle l5 on the horizontal plane. The curve W of the speeds can readily be deduced therefrom.

In this diagram of Fig. 4, the curve V has also been drawn, so that it can be easily compared with the curve V. It can be seen that the maximum of the curve Vis distinctly lower than the maximum of the curve V If V designates the maximum of the curve V it will be seen that that of the curve V is about 1.5- V.

In Fig. 5, in the same manner as for Fig. 4,

the second movable system during the period in whichthe feeler 9 moves away from the axis of rotation of the pattern blade 4.

The curve E of the distances and the curve V of the speeds is obtained, the latter curve having been inserted in Fig. 4. This curve is extremely accentuated and it canbe seen that its maximum is equal to threetimes that of the curve V The fact can then be satisfactorily explained that in the machines of the kind shown in Fig. 3, the drawback already observed in the machines according to Fig. l is considerablyamplified, that is to say that the movable system 9'--|'|-'-l3' breaks contact with the pattern blade 4 and the blank 5 as through it were projected violently outwards.

The invention is the result of. the comparison of the curves V, V and V It is obvious'thai the curve W is by far the most advantageous, and that it would be of the greatest interest to construct a machine in which the two movable systems possess this speed diagram V In order to obtain this result, it obviously suflices that the condition set forth in the preamble be fulfilled, that is to say that during the period in which the feeler or the tool moves away from the axis of rotation of the pattern blade or oi the blank, the quadrilateral formed by (see Fig 4) the axis of rotation l4 of the blade, the axis l6 of oscillation of the lever II, the. axis Iii (for and in Fig. 5 said are which is shown at MN is blade distinctly less than 90 The machine according to Fig. 6 fulfills these conditions.

The first movable system comprises the fe'elei 9 which is pivoted at on a lever itself pivoted at 2| on the carriage 6. The lever 20 is connected by a connecting rod 22 to a second level 23 identical with the lever 20 and pivoted at 24 on the carriage 6. The connecting rod 23 is pivoted at 25 and 26 on the levers 20 and H fand the pivot pins 2l--24-25 -26 form a parallelograin. The tool it is mounted on the lever 23 and it is obvious that it cuts on the blank E an identical contour. to that of the blade 4, under the same conditions as the tool l3 of Fig. 3 The second movable system is composed in exactly the same manner, but all'its members are arranged symmetrically-relativelyto the axes o1 rotation of the blade 4 or of the blank 5.. It'i: therefore not necessary to describe this'seconc' system, of which the members are'designated b5 the same reference numerals with'an index. In Fig. 6, at 21 has been shown the pulley 01 the motor which actuates the tools l3 and I3 for example by means of belts which have been shown in chain dotted lines, but it is obviom that any other method of drive could be utilized.

It would be advantageous, in order to furthei decrease the minimum V of the, speeds,-to reduce the leverarms such as lS-Il to the smallest possible dimension, and it will be noted that the arrangement adopted facilitates this reduction. .In fact, in the case of the movable systeir 9'l3 of Fig. 3, the distance l5'l6 cannot be reduced below a minimum which would correspond to the propping effect of the end of the blade against the feeler 9', which would of course absolutely prevent the operation. On the contrary, in the arrangement of Fig. 6, the decrease of the lever arm 2l- -l5 is advantageous in all respects and it will be of the greatest advantage to reduce said lever arm to the minimum possible.

Fig. 7 is a diagram relating to the machine of Fig. 1 in which the blade 4 is shown by a straight line. .Said straight lineis rotated in the direc-. tion of the arrow f. It drives before it the roller" 9, of which the spindle I5 moves on the straight line I. The points of contact of the roller 9 and the straight line '4' are shown by small points. The curve of the distances travelled along the straight line by the point of contact of the roller is plotted'in Fig. 8, the angles travelled through by 4 being plotted along OK and the paths travelled through by the roller 9 on the straight line s being plotted along OY. It will be seen that this curve rises considerably towards its end, that is to say that the speed is the greatest towards the end of the blade. The tangent t1 has been drawn at the end of the curve; said tangent t1 forms the angle m-with the axis OK. The speed is, as known, equal to the trigonometrical'. tangent of the angle on. Now, an excess of speed offeed is particularly dangerous at this spot, and this drawback is exceedingly serious. To reduce same, it becomes necessary to'limit the speed of rotation of the pattern blade 4 and'of the blade to be worked 5, thereby decreasing the-efllcieney of the machine.

The curve of the distances which is plotted for theymovement of the point of contact between the roller 9 (Fig. 3) -and' the pattern blade 4 and which is the object of Figs. 9. and 10, shows an improvement relatively to Fig. 8, the tangent t2 making a smaller angle 0:2 with OX. On the other hand, the'curve of the distances which is plotted for the movement of the point of contact between the roller 9 and the pattern blade 4 and which is shown in Figs. 11 and 12 is on the contrary still worse than that of Fig. 8, the tangent is making a wide angle as with OX. Such a machine is therefore again very defective. I

As explained above, the machine of. Fig. 6 overcomes these drawbacks. The very satisfactory results it gives arecapable of being further improved by one of the means which are the object of the present invention. Said means has the, purpose and the effect of making the speed of displacement of the point of contact of the rollers or the tools on the blades still more regular. i

For the explanation of this invention, the curve has been drawn in Fig.-13, which would be the locus of thecentres 15 of the rollers 9 if the speed of displacement of the point of contact with the blade were constant. In order to draw this curve, successive positions of the blade 4 have been drawn which are in equally spaced angular relation; on these curves the successive positions of the point of contact have been shown, which are in equally spaced relation and which therefore give a spiral of Archimede C1. By drawing at these points perpendiculars' equal to the radius of the roller, the required curve C:

can obviously be deduced therefrom. It can be of the blades.

tangent varies very rapidly.

The object of the invention is to substitute for this curve, an arc of a circle which is the nearest approach possible to same, and for thispurpose it is obvious that it is advantageous to select the position of the pivot pins of the Ilevers supporting the rollers and the tools in a different manner from the previous one. In the embodiment shown by'Figure 6, the pivot pins are placed in a vertical plane containing the axis of rotation According to another feature of the invention, said pins are placed outside "said plane, as shown at 30, in such a manner that thecircular path C3 of the spindles l5 of the rollers 9 is tangential to the horizontal plane passing through the axis of rotation of the blades, or even passes through said plane.

Fig. 14 gives the curve of-the distances in this case, and it can be 'seen that the tangent t4 makes an angle at substantially less than in the previous cases. 1 This gain is the more substantial as for these single values the trigonometrlcal On the other hand, the machine shown in Fig. 6 sometimes creates certain difficulties owing to its height. [In many cases, it would be very desirable to arrange the. axes of rotation 2| and 24" at the 10w; part, like the axes 2| and 24. The

invention enables this arrangement tojbe effected without however producing the drawbacks previously mentioned.

Fig. l5 shows an arrangement in which the trajectory shown in Fig. 13."

In fact, Fig. 16 shows at C5 the curve of .the distances, and it 'can be seen that thetangent t5 at the end of said curve makes an angle aswhich is of considerable size. But it will benoted that it is possible to improve this arrangement, as shown in Fig. 17, by using rollers 9 of greater diameter. The curve C6 of Fig. 19 shows the result obtained by this. means; the tangent is forms an angle aewith theaxis OX, which is much smaller than the angle as.

Under these conditions, according to'an important feature of the invention, the axes of oscillationv of the two movable systems can be arranged at the low part of the machine, as shown-in Fig. 18. One of said movable systems has its axis of oscillation arranged at 32 and the other at 33. The axis 32 is arranged in the most advantageous manner, and consequently theroller 9 is of reduced diameter.

-The axis 33 shown on the same horizontal plane MN as the axis 32'is substantially less :re,

mote from the vertical plane passing through the blade in its starting position, and the roller,9' is of much larger diameter. This arrangement is quite characteristic, and it can be defined as follows: when the rollers 9 and 9' are in the posishown in Fig. 18), the spindles l5l5 of said rollers formwith the pivot pins 32 and 33 a convex quadrilateral and no longer a. triangle as in the device of Fig. 3,'or a broken line as in the device of Fig. 6. Furthermore, the levers 20 and 20' whichcarry thespindles l5 and I5 are not oi the same length, the lever 20 being larger than the lever 20; in addition, the lever I tion in which'they are nearest each other (as angle than that which is formed by the lever .20 with the. direction l5--l5. Finally, the roller arrangement.

9' is of greater diameter than the roller 9. It will be observed that it is not necessary for the direction 3233 to be parallel with the direction iii-l5. I

Fig. 19 shows, in a less diagrammatical manner than Fig. 18', a machine according to the invention. In'this example, the axes 3,2 and 33 are arranged in the same horizontal plane MN as in Fig. 15, but it is pointed out that this arrangement is in no' Way indispensable. The lever 20 carrying the spindle of the roller 9 is connected to the lever 20 carrying the spindle I5 of the tool l3 by a bar 22 similar to the one shown in Fig. 9. This system is balanced by the counterweights shown at 34. There furthermore exists an adjustable counterweight 3 5 to which further reference will be made hereinafter. Said counterweight is intended to hold the roller 9 in contact with the pattern blade 4.

The lever 23 which carries the roller 9' is connected by the bar ;22' to the lever 23 which carries the tool I3;- the wholearrangement is balanced by the counterweights 34 and there is also an adjustable counterweight 35 for this Just as in .the previous examples, the shafts 32 and 33 are supported by a carriage 6 which is movablelongitudinally parallel with the axes of rotation of the blades 4 and'5.

The counterweights 35 and 35' are adjustable I not only as regardstheir lever arms, but also as regards the angular position of said lever arms. For this purpose, the adjustment in length is effected by unscrewing the nuts 46 andby adjusting the position of the counterweights 35 and 35" on the rods 31 and 3'1, which are respectively fixed to the levers 20 and 23. For the adjustment of the angular position of the lever arms, the following arrangement has been adopted; the counterweights 35-35 are constructed in such a manner that their centre of gravity is not located on the axis of the rods 31 and 31; consequently, by rotating the counterweights 35 and 35' on the rods 31 and 31', the adjustment of the angular position of the lever arm of said counterweights relatively to the levers 20 and 23 is obtained without difficulty-since the centres of gravity are raised or lowered.

Althoughv the machine of Fig. 19 has been shown for cutting a single blade, it is quite obvious' that exactly identical arrangements could be adopted for a plurality of blades; it would sufiice to have a plurality of systems 20'23' respectively connected to the bars 22-22 which had been suitably extended. It will be observed furthermore that owing to the arrangements adopted, the stresses exerted by the pattern blade 4 on the rollers 9 or 9, during the time said blade pushes same against the effect of their counterweights, are always maintained within reasonable limits, because the law of variation of such stresses does not give rise to great differences between them in the successive positions of the blade. This result cannotbe obtained in the machines of the type of Fig. 1, without an increase in the diameter of the rollers which quickly'becomes objectionable, the duration of useful work being inversely proportional to the diameter of the roller.

What I claim as my'invention and desire to secure by Letters Patent is:

1. In a machine for the manufacture of propeller blades by copying and including a pattern blade, 9. blank blade, means for rotatively supporting and for synchronously causing to rotate the pattern blade and the blank blade about two parallel geometric axes, two feelers or rollers arranged on both sides of the pattern blade, rocking levers for supporting the said feelers or rollers, means for applying the feelers or rollers against the pattern blade, tools arranged on both sides of the blank blade, rocking levers for supporting the said tools, means for operatively connecting-the tools rocking levers and the corresponding feeler rocking levers, the feature which consists in that in their nearest position, and second1y,at unequal distances on both sides of a second reference plane at right angles with the first reference plane and which contains the geometric axis of revolution of the pattern blade, the greatest distance corresponding to the geometric axis of oscillation which is at the left hand of the second reference plane for an observer who, placed in ,the

said second plane and on the same side as that of the geometric axis of oscillation relatively to the first plane, would see the pattern blade rotating in a clockwise direction.

2. In a machine for the manufacture of propeller blades by copying according to claim 1, the feature which consists in that the lengthxof the rocking lever the geometric axis of oscilation of which is at the greatest distance from the second reference plane, is greater than the length of the other rocking lever.

3. In a machine for the manufacture of propeller blades by copying according to claim 1, the feature which consists in that the diameter of the feeler or roller carried by the rocking lever the geometric oscillation axis of which is at the greatest distance from the second reference plane, is greater than the diameter of the feeler or roller carried by the other rocking lever.

4. In a-machine for the manufacture of propeller blades by copying, according to claim 1, the feature which consists in that the length of the rocking lever the geometric oscillation axis of which is at the greatest distance from the second reference plane, and the diameter of the feeler or roller carried by the said lever, are greater than the length of the other rocking lever and the diameter of the other feeler or roller respec- 

